1. Field of the Invention
The present invention relates to a ceramic burner, particularly a ceramic burner of a hot-blast stove having a central burner duct for supply of a first combustion component, such as a combustible gas, and an outer annular duct disposed coaxial to the central burner duct for supplying a second combustion component, such as air.
2. Description of the Related Art
Conventionally, ceramic burners have been provided with a single ring nozzle having a plurality of openings extending from the outer annular duct to a burner mouth which extends outwardly from the central burner duct.
A burner of this type is disclosed in Federal Republic of Germany DE-OS No. 1551777, in which a single ring nozzle is provided having openings connecting the outer annular duct to the burner mouth for combining the first and second combustion components. In such a configuration, however, a deficient flame stabilization results, in particular when the throughput of the combustion media is high. When such a deficient flame stabilization is present, problems such as burn-out of the flame and oscillations of the flame can occur. Oscillations of the flame are particularly troublesome in that the burner can be excited to a pulsation condition, resulting in a high mechanical stress on the burner and, under some circumstances, further resulting in the generation of a significant level of noise within the hot-blast stove.
A second ring nozzle is disclosed in Federal Republic of Germany DE-OS No. 2809521. The second ring nozzle is located below the burner mouth, relative the flow direction of the combustible gas, and includes openings extending from the outer annular duct and open at the central burner duct. According to this configuration, a pre-mixing of the combustible gas and air is obtained. Pre-mixing in this manner, however, also results in a propensity of the burner to enter into a pulsation condition.
It is noted that Federal Republic of Germany DE-AS No. 2541991 also discloses a burner having a first ring nozzle open at the burner mouth and a second ring nozzle open at the central burner duct.